“For a President to follow that historic step forward by unilaterally walking backwards from science and backwards from leadership on behalf of polluters and fringe ideologues may be the most self-defeating action in American history,” the former Massachusetts senator said in a statement.

The United States will join Nicaragua and Syria as the only countries that are not part of the agreement. Kerry said Trump’s decision isolates America from the rest of the world.

“The President who promised “America First” has taken a self-destructive step that puts our nation last,” Kerry said. “This is an unprecedented forfeiture of American leadership which will cost us influence, cost us jobs, and invite other countries to walk away from solving humanity’s most existential crisis.”

(Photos by Zach Gibson and Saul Loeb/AFP/Getty Images)

Kerry called for states and cities to continue honoring the ideals of the Paris agreement, which requires participants to present plans to reduce their carbon emissions. Massachusetts Gov. Charlie Baker and Boston Mayor Marty Walsh echoed those sentiments Thursday.

“Despite today’s announcement, Massachusetts is aggressively working to exceed the goals of the Paris Agreement on the state level, while growing our economy through clean energy innovation and environmental stewardship,” Baker said. “In Massachusetts and around the world, climate change is a shared reality and our ability to rise and respond to this challenge will shape future generations.”

Boston City Hall lit up green after President Trump opted out of Paris Accord (WBZ-TV)

Boston City Hall was lit up green Thursday night, and Walsh tweeted “Boston stands with the environment.” He said the city will continue efforts to be carbon neutral by 2050.

“Withdrawing the U.S. from the Paris climate agreement isn’t just a setback, it’s irresponsible,” Walsh said. “Boston will not standby given what’s at stake.”